My gut is telling me that unless you are selecting your chiller to function at 120%, or in effect making that the "design" condition, you should use the 100% capacity for your curve. <br><br><div class="gmail_quote">
On Wed, Nov 3, 2010 at 8:08 AM, James Newman <span dir="ltr"><<a href="mailto:James.Newman@me-engineers.com">James.Newman@me-engineers.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Nick,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I am also working away at the unsolved mystery of creating a
chiller curve. I have come to the conclusion that if you are only
inputting an EIR-PLR curve, you must do this at ARI rated conditions
because the other two curves, (CAP and EIR) are equest defaults at ARI
conditions. I failed at making all three curves as my results ended up
cutting the energy use to about an 1/8. I think in order to make the (CAP and
EIR) curves you must have a full range of chiller supply temps and condenser
supply temps. The information I was provided was with the same supply and
condenser temps with the variables being load and kw/ton. I’m going to
try to construct a new curve with conforming everything to ARI conditions and
see what the results come back as.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(135, 193, 57);">James M. Newman, EIT, LEED AP</span></b></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);">Project Engineer / Energy Analyst</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(135, 193, 57);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><a href="http://www.me-engineers.com/" target="_blank"><b><span style="color: rgb(135, 193, 57);">M-E Engineers, Inc.</span></b></a></span><b><u><span style="font-size: 11pt; color: rgb(135, 193, 57);"></span></u></b></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);">10055 west 43rd avenue</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);">wheat ridge, co 80033</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);"> </span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);">office: 303.421.6655</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(72, 73, 74);">direct: 720.898.3148</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><a href="mailto:catie.williams@me-engineers.com" target="_blank"><span style="font-size: 10pt; color: rgb(89, 89, 89);">james.newman@me-engineers.com</span></a></span><span style="font-size: 10pt; color: rgb(89, 89, 89);"></span></p>
</div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div>
<div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;">
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Nick
Caton<br>
<b>Sent:</b> Wednesday, November 03, 2010 9:03 AM<br>
<b>To:</b> Carol Gardner; <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><div><div></div><div class="h5"><br>
<b>Subject:</b> Re: [Equest-users] Chiller Curves (oh boy!)</div></div></span></p>
</div>
</div><div><div></div><div class="h5">
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Thanks for the response Carol!</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">That 120% load case is what I’m getting at – let me
try to explain a little further:</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">In the DOE2 help files, the vocabulary for centrifugal chillers
is “design capacity” and “maximum capacity,” where
“design” means the capacity at the rated or designed conditions (at
which you define / specify your chiller), and “maximum” means the
capacity the chiller is really capable of under the same conditions if it runs
balls-out (maximum power to the refrigerant drive).</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">The help file excerpt I copied below with the red line is pretty
explicitly telling us to normalize the part load values to the <u>maximum</u>
capacity for centrifugal chillers. I’ve highlighted a second line
for clarity. The EDR guidelines I linked below are saying you can instead
normalize to the <u>design</u> capacity for the EIR-PLR curve if that’s
all your field measurements or manufacturer rep can provide.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I’m asking – are both approaches right? </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">My first and second questions are kinda tied together… How
would choosing to normalize to either the maximum or design conditions affect
how we should handle the DESIGN-PLR ratio, if at all?</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">~Nick.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><img src="cid:image001.jpg@01CB7B36.98158A30" alt="cid:489575314@22072009-0ABB" border="0" height="37" width="119"></span><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b><b><span style="color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span><span style="font-size: 7.5pt; color: rgb(204, 153, 0);"></span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">25501 west valley parkway</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">olathe ks 66061</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">direct 913 344.0036</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">fax 913 345.0617</span></p>
<p class="MsoNormal"><i><span style="font-size: 10pt; color: rgb(45, 77, 94);">Check out our new web-site @ </span></i><span style="font-size: 11pt; color: rgb(31, 73, 125);"><a href="http://www.smithboucher.com" title="blocked::www.smithboucher.com" target="_blank"><span style="font-size: 10pt;">www.smithboucher.com</span></a></span><u><span style="font-size: 10pt; color: blue;"> </span></u><span style="font-size: 11pt; color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> Carol Gardner
[mailto:<a href="mailto:cmg750@gmail.com" target="_blank">cmg750@gmail.com</a>] <br>
<b>Sent:</b> Tuesday, November 02, 2010 10:04 PM<br>
<b>To:</b> Nick Caton<br>
<b>Cc:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Chiller Curves (oh boy!)</span></p>
</div>
<p class="MsoNormal"> </p>
<p class="MsoNormal" style="margin-bottom: 12pt;">Let me take a crack at this. If
by design capacity you mean the chiller running at 100% load, you would create
the curve(s) by normalizing around your ARI design conditions i.e. the PLR
curve would be 1.0 at this point, call it ARI Cap and the other points would be
90% Cap/ARI Cap, 80% Cap/ARI Cap, etc. The same would go for your temp curves.
If, however, your chiller is operating at 120%, or some such other level, I
would normalize the curve around the ARI design conditions of the chiller at
120%. I had to do this for a VRV hp that was selected at the 120% design
condition.<br>
<br>
I find this from the DOE2 manual the most helpful:</p>
<div style="border-width: 1pt medium; border-style: solid none; border-color: rgb(153, 153, 153) -moz-use-text-color; padding: 0in;">
<div>
<div>
<p> </p>
</div>
</div>
</div>
<div>
<div>
<p class="MsoNormal"><a href="http://volume2dictionary.htm" target="_blank">Volume 2: Dictionary</a><span> > </span><a href="http://hvaccomponents.htm" target="_blank">HVAC
Components</a><span> > </span><a href="http://curvefit.htm" target="_blank"><span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">CURVE</span>-<span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">FIT</span></a><span> > </span><a href="http://inputtypedata.htm" target="_blank">INPUT-TYPE
= DATA</a></p>
</div>
<h5>INDEPENDENT-2</h5>
<p>Used for all <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curves</span>
having two independent variables. A list of up to twenty values of the second independent
variable. The number of values should be the same as for DEPENDENT.</p>
<p><b><span>Example
1</span></b>: defining a <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span>
by inputting a set of data points.</p>
<p>A packaged system (PZS) has cooling performance
significantly different from that used in the default model. The
manufacturer lists the data shown in Table 46, for cooling capacity, at 2000
cfm design air flow rate, as a function of outside dry-bulb temperature and
entering wet-bulb temperature.</p>
<p><a name="12c12482e002036e__Ref490744859"></a><a name="12c12482e002036e__Ref490744804"></a>Table
46 Cooling capacity (kBtu/hr) vs. temperature</p>
<div style="margin-top: 2pt; margin-bottom: 2pt;">
<div align="center">
<table style="border-collapse: collapse;" border="0" cellpadding="0" cellspacing="0">
<tbody><tr>
<td rowspan="2" style="width: 1in; border: 1pt solid windowtext; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt;" valign="top" width="96">
<p style="margin-top: 0in; text-align: center;" align="center"><b>Outside<br>
Dry-bulb</b></p>
</td>
<td colspan="3" style="width: 3in; border-width: 1pt 1pt medium medium; border-style: solid solid none none; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color;" valign="top" width="288">
<p style="text-align: center;" align="center"><b>Entering
Wet-bulb</b></p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>72F</b></p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>67F</b></p>
</td>
<td style="width: 1in; border-width: medium 1pt 1pt medium; border-style: none solid solid none; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>62F</b></p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">85F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">69</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">65</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">60</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">95F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">68</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">63 (ARI)</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">57</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">105F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">65</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">60</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">53</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt 1pt; border-style: none solid solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">115F</p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">62</p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">55</p>
</td>
<td style="width: 1in; border-width: medium 1pt 1pt medium; border-style: none solid solid none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;" valign="top" width="96">
<p style="margin-bottom: 0.0001pt; text-align: center;" align="center">49</p>
</td>
</tr>
</tbody></table>
</div>
</div>
<p> </p>
<p>In this example the independent variables are the entering
wet-bulb temperature and the outside dry-bulb temperature. Because there are
two independent variables and they have units of temperature, we input a <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span> of TYPE BI-QUADRATIC-T
using the given data points. The dependent variable is not the cooling capacity
listed in the table but rather the cooling capacity divided by the cooling
capacity at the ARI rating point (95 F outside dry-bulb and 67 F entering
wet-bulb). In other words, the capacities should be normalized to the ARI
rating point., as shown in Table 47</p>
<p><a name="12c12482e002036e__Ref490745029">Table </a>47 Normalized
capacity vs. temperature</p>
<div style="margin-top: 2pt; margin-bottom: 2pt;">
<div align="center">
<table style="border-collapse: collapse;" border="0" cellpadding="0" cellspacing="0">
<tbody><tr>
<td rowspan="2" style="width: 1in; border: 1pt solid windowtext; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt;" valign="top" width="96">
<p style="margin-top: 0in; text-align: center;" align="center"><b>Outside<br>
Dry-bulb</b></p>
</td>
<td colspan="3" style="width: 3in; border-width: 1pt 1pt medium medium; border-style: solid solid none none; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color;" valign="top" width="288">
<p style="text-align: center;" align="center"><b>Entering
Wet-bulb</b></p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>72F</b></p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>67F</b></p>
</td>
<td style="width: 1in; border-width: medium 1pt 1pt medium; border-style: none solid solid none; background: none repeat scroll 0% 0% aqua; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center"><b>62F</b></p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">85F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">1.095</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">1.032</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">0.952</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">95F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">1.079</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">1.0 (ARI)</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">0.905</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt; border-style: none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">105F</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">1.032</p>
</td>
<td style="width: 1in; padding: 0in 5.4pt;" valign="top" width="96">
<p style="text-align: center;" align="center">0.952</p>
</td>
<td style="width: 1in; border-width: medium 1pt medium medium; border-style: none solid none none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext -moz-use-text-color -moz-use-text-color;" valign="top" width="96">
<p style="text-align: center;" align="center">0.841</p>
</td>
</tr>
<tr>
<td style="width: 1in; border-width: medium 1pt 1pt; border-style: none solid solid; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">115F</p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">0.984</p>
</td>
<td style="width: 1in; border-width: medium medium 1pt; border-style: none none solid; padding: 0in 5.4pt; border-color: -moz-use-text-color -moz-use-text-color windowtext;" valign="top" width="96">
<p style="text-align: center;" align="center">0.873</p>
</td>
<td style="width: 1in; border-width: medium 1pt 1pt medium; border-style: none solid solid none; padding: 0in 5.4pt; border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;" valign="top" width="96">
<p style="margin-bottom: 0.0001pt; text-align: center;" align="center">0.778</p>
</td>
</tr>
</tbody></table>
</div>
</div>
<p> </p>
<p>The <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">CURVE</span>-<span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">FIT</span> input will look like the
following:</p>
<p>CAP-<span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">CURVE</span>-1
= <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">CURVE</span>-<span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">FIT</span><br>
TYPE
= BI-QUADRATIC-T<br>
INPUT-TYPE = DATA<br>
DEPENDENT =
(1.000,1.079,0.905,1.032,0.952,0.841,<br>
0.984,0.873,0.778,1.095,1.032,0.952) ..<br>
IN-TEMP1 =
( 67, 72, 62, 72,
67, 62,<br>
72, 67, 62,
72, 67, 62) ..<br>
IN-TEMP2 =
( 95, 95, 95, 105, 105,
105,<br>
115, 115, 115,
85 85, 85) ..</p>
<p><b><span>Example
2:</span></b> Defining a <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span>
by inputting coefficients</p>
<p>We want a furnace to have a constant efficiency as a
function of part load. To do this we must replace the default FURNACE-HIR-FPLR
with a <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span> that will give
a constant efficiency. The <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span>
TYPE is QUADRATIC in the part load ratio (PLR). PLR correction <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curves</span> are always multiplied by
the unit capacity, not the load, to obtain the energy (fuel or electricity)
use. Thus the <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">curve</span> we want
is: 0.0 + 1.0*PLR + 0.0*PLR*PLR. The input will look like:</p>
<p>New-Furnace-HIR-fPLR = <span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">CURVE</span>-<span style="color: white; background: none repeat scroll 0% 0% rgb(49, 106, 197);">FIT</span><br>
TYPE
= QUADRATIC<br>
INPUT-TYPE = COEFFICIENTS<br>
COEFFICIENTS = (0.0,1.0,0.0) ..</p>
<p>Then in the SYSTEM command we include:</p>
<p> FURNACE-HIR-FPLR = New-Furnace-HIR-fPLR</p>
</div>
<p class="MsoNormal" style="margin-bottom: 12pt;"> </p>
<div>
<p class="MsoNormal">On Tue, Nov 2, 2010 at 3:21 PM, Nick Caton <<a href="mailto:ncaton@smithboucher.com" target="_blank">ncaton@smithboucher.com</a>> wrote:</p>
<div>
<div>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">Hi everyone!</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);">I think I have <u>finally</u> wrapped my mind completely
around custom chiller performance curves for a centrifugal VSD chiller.
I’ve got a few specific questions now that I’m on the other side of
the fence:</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">1.</span><span style="font-size: 7pt; color: rgb(31, 73, 125);"> </span><span style="color: rgb(31, 73, 125);">Is it necessary for the data points of a part load
efficiency curve (EIR-FPLR&dT in my case) to originate from data with a 1.0
(100%) PLR ratio corresponding to a maximum vs. a design load capacity?
>From what I gather in <a href="http://www.energydesignresources.com/Portals/0/documents/DesignGuidelines/EDR_DesignGuidelines_%20HVAC_Simulation.pdf" target="_blank">the EDR reference</a> (re: “Method 2” on PDF page
32/65), this curve can be generated using part-load readings assuming a <u>design</u>
capacity at the 100% loading mark… but the DOE2 help entry for
“EIR-FPLR” seems to suggest otherwise (copied below – see
highlighted line).</span></p>
<p><span style="color: rgb(31, 73, 125);">2.</span><span style="font-size: 7pt; color: rgb(31, 73, 125);"> </span><span style="color: rgb(31, 73, 125);">If the above part load efficiency curve is created based on
data where the 100% loading point corresponds to the maximum (not design)
capacity, should “DESIGN-PLR” (the ratio of design to maximum
capacity) be set to 1.00 and the capacity of the chiller be specified at its
maximum (not design) for the design/rated conditions? As I write this
question it sounds like I’m chasing my tail – someone straighten me
out =)!</span></p>
<p><span style="color: rgb(31, 73, 125);">3.</span><span style="font-size: 7pt; color: rgb(31, 73, 125);"> </span><span style="color: rgb(31, 73, 125);">When you veterans finish a project with sets of custom
performance curves, do you have any suggestions for a naming scheme for future
reference/re-use? I’m currently thinking to keep the curves grouped
in an .inp snippet I for importing along with an equipment cutsheet… but
I’m certain I’ll forget the all the details as quickly as humanly
possible when this project is behind me…</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal" style="margin-left: 0.25in;"><span style="color: rgb(31, 73, 125);"> ~Nick</span></p>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"> </span></p>
<div>
<p class="MsoNormal"><span style="color: rgb(31, 73, 125);"><img src="cid:image001.jpg@01CB7B36.98158A30" alt="cid:489575314@22072009-0ABB" border="0" height="37" width="119"></span></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">25501 west valley parkway</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">olathe ks 66061</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">direct 913 344.0036</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; color: rgb(45, 77, 94);">fax 913 345.0617</span></p>
<p class="MsoNormal"><i><span style="font-size: 10pt; color: rgb(45, 77, 94);">Check out our new web-site @ </span></i><span style="color: rgb(31, 73, 125);"><a href="http://www.smithboucher.com" title="blocked::www.smithboucher.com" target="_blank"><span style="font-size: 10pt;">www.smithboucher.com</span></a></span><u><span style="font-size: 10pt; color: blue;"> </span></u></p>
</div>
<p class="MsoNormal"><b><span style="font-size: 10pt;">EIR-FPLR</span></b></p>
<p class="MsoNormal">Takes
the U-name of a curve that adjusts the electric input ratio as a function of</p>
<p class="MsoNormal" style="margin-left: 0.5in;"><span style="font-family: Symbol;">· </span><u>The part
load ratio (PLR)</u> – The PLR is defined as the ratio of the
hourly load to the hourly capacity; Load / Cap<sub>hour</sub></p>
<p class="MsoNormal" style="margin-left: 0.5in;"><span style="font-family: Symbol;">· </span><u>The
evaporator/condenser dT</u> - The temperature differential between the
condenser and leaving chilled-water. The meaning of the condenser
temperature varies according to condenser type. </p>
<p class="MsoNormal" style="margin-left: 2.7pt;">For most chillers, the dT has a relatively small effect on
part-load performance. However, for variable-speed centrifugal chillers, the
effect of dT is as important as the PLR. This is because the pressure
rise across the impeller is proportional to the square of the impeller’s
speed. Unless some form on condenser temperature relief is employed to reduce
the temperature (and pressure) differential across the chiller at part load,
the performance of a variable-speed chiller may not be significantly different
than that of a constant-speed chiller.</p>
<p class="MsoNormal">To
model power consumption as a function of the PLR only, use a CURVE-FIT of TYPE
= QUADRATIC or CUBIC. To model as a function of both PLR and dT, use a
BI-QUADRATIC-RATIO&DT curve. <b><span style="color: red;">The curve must be
normalized to 1.0 at full load and the rated temperature differential. </span></b></p>
<p class="MsoNormal"><b><span style="color: red;">Note that, for centrifugal chillers, ‘full load’
is defined as the ‘maximum capacity’, not the ‘design
capacity’.</span></b> Refer to the DESIGN-PLR keyword for more
information.</p>
<p style="margin-bottom: 12pt;"> </p>
</div>
</div>
<p class="MsoNormal" style="margin-bottom: 12pt;"><br>
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</div>
<p class="MsoNormal"><br>
<br clear="all">
<br>
-- <br>
Carol Gardner PE</p>
</div></div></div>
</div>
</blockquote></div><br><br clear="all"><br>-- <br>Carol Gardner PE<br>
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